there are a lot of great finishes out there but many people are intimidated by the whole finishing process so we've been making videos that help the average hobbyist woodworker get great results from common wood finishes these videos i think are the best out there because they cover a lot of important points that others just seem to skip over below this video i'll link to a playlist of our finishing videos that we've made so far just expand the video description or you can also find it pinned to the top of the comments section you really should check it out there is a lot to learn in there now today i want to talk about oil-based polyurethane because it's a very durable finish that's suited for both indoor and some outdoor projects it's not difficult to apply but i think my method will give you the best results so first you're going to prepare your surface by sanding really well we've made a comprehensive sanding tutorial that explains how to properly sand what grits to use raising the grain all that stuff you'll find that in the playlist below as well but for the sake of this video i'm going to suggest sanding to no higher than 150 180 if you plan to apply a wood stain or go to 220 240 if you plan to apply just polyurethane anything finer than 240 is a waste of time with this type of finish i also recommend hand sanding your final grit in this case i'm using 220 and going with the grain this will disguise the fine scratches that the sandpaper leaves behind now we're dealing today with oil based poly if you're applying this in enclosed space you really should wear a respirator with activated charcoal filters now if you can work in a well ventilated area that's up to you whether you want to wear a respirator but honestly if you're going to be working around any oil-based finish for more than just a few minutes it's probably a good idea to protect yourself unless you have excess brain cells to spare the application process for water-based poly is very similar to oil-based poly but we'll make a separate video about that down the road oil-based poly typically comes in three sheens gloss semi-gloss and satin all of them must be mixed thoroughly but semi-gloss and especially satin must not only be mixed well to start out it also must be mixed again between coats and perhaps periodically while you work if it's taking you more than a half hour or so to apply a single coat that's because satin and semi-gloss finishes contain flattening agents to reduce their naturally glossy sheen and you have to keep those flatteners suspended in the liquid or you're going to get an uneven finish so keep it mixed and notice i said mix it don't shake polyurethane you don't want a bunch of air bubbles in there so stir it well then stir it some more and stir it often i never like to use poly straight from the can you want to get rid of any crud or partially crystallized finish that may be in there so get yourself some disposable strainers you can find these wherever you bought your can of finish after it's mixed pour some through the strainer into a clean container and let it slowly run through that fine mesh this will help with air bubbles as well you don't have to strain the whole can just do what you think you're going to need for the coat you're about to apply now you have to decide if you're going to use the poly as it is or if you'll need to thin it any poly can be thinned water-based poly is thin with water oil-based poly is thinned with mineral spirits or other thinners whether too thin and how much to thin depends on a lot of factors and i don't want to complicate this more than i have to so simply put if you're going to brush it on you probably don't need to thin it right out of the can unless it's an old can that's kind of started to thicken up a little bit this is the consistency you're looking for if you do intend to brush it on if you're going to wipe on the poly with a cloth then you will need to thin it by as much as 50 and we'll get to that shortly so the question is should you brush it on or should you wipe it on honestly if you're new to this whole process i think you should probably wipe it on it's just easier to wipe on poly but since you have to thin the finish so much to wipe it on easily you do have to be more careful to avoid things like runs especially on vertical surfaces and you're going to have to apply more coats overall brushing on poly on the other hand involves a little bit more technique but it's worth learning to do i'm going to show you both in this video first we'll brush it on then we'll wipe it on of course to brush it on you need the right brush make sure that it's labeled for oil based finishes not for latex paint this usually means a natural bristle brush white china bristles come from hogs they're very absorbent so they hold the finish well and the solvents in the finish won't break this type of brush down as they will a synthetic brush so the bristles will remain straight and smooth i'm going to be working on a scrap of plywood just to demonstrate the process but i assume that you've sanded yours well and you've cleaned up all the dust i like to wipe mine with denatured alcohol but you could use a slightly water dampened cloth i'm also assuming you're working in a relatively dust free environment if it's the same place where you did your sanding you probably should let the dust settle for a couple hours then give your project its final wipe down and then you'll be ready to finish so dip your brush no more than halfway into the finish wipe off the excess and begin applying it spread it out well it's better to apply three or more thinner coats than two thick coats and as much as possible brush with the grain not across it it is very important to always work wet this means you shouldn't try to brush wet poly over a spot that's already begun to dry for example i like to work down the length of the surface in narrow sections but i must keep each section narrow enough or i must work fast enough so that my next stripe can overlap this first one before it has begun to dry i don't want to put new wet finish over sticky partially dry finish this could take a little bit of planning especially if you're working on a large surface like a table top but in most cases if you're working out of the sun in a relatively cool place you should have enough time to cover the whole surface before it begins to dry but keep an eye on it remember to brush with the grain as i work i like to go back over each section with long parallel strokes this will help to even everything out you don't want areas that are significantly thicker than other places you can see how uneven this looks when the light hits it but as long as the finish is still wet i can go back and even this out what i like to do is squeeze any excess finish from my brush so that it's all but dry then i go back over the surface using just the tip of the brush with long light parallel strokes that run the full 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